Reporting period: December 2019 – June 2020
Proposal stage of development: Options analysis—completed
Responsible agency: Department of Natural Resources, Mines and Energy1
The Paradise Dam Options Assessment investigated long-term options to ensure water security for the region for future economic growth and to maintain community safety.
Paradise Dam is located approximately 20 kilometres north-west of Biggenden and 80 kilometres south-west of Bundaberg on the Burnett River. It is owned, managed and operated by Sunwater.
During the 2013 floods, extensive scour occurred downstream of the primary spillway. Sunwater immediately repaired the scour and downstream toe of the dam.
Following a comprehensive safety review and risk assessment, Sunwater identified that further upgrades are required to ensure the dam meets the latest design standards and operates safely during extreme weather events.
Completed in February 2020, Building Queensland’s report assessed long-term options to ensure water security for the region for future economic growth and to maintain community safety.
The proposal investigated the following options:
- Option 1: maximum primary spillway height (equivalent to a primary spillway level of RL67.6m)
- Option 2: reduce maximum primary spillway height by 5m (equivalent to a primary spillway level of RL62.6m)
- Option 3: reduce maximum primary spillway height by 10m (equivalent to a primary spillway level of RL57.6m)
- Option 4: reduce maximum primary spillway height by an optimised level (between 5m and 10m) to maintain water security
- Option 5: decommission the dam.
Building Queensland recommended in the options assessment report that further technical investigations, structural testing and sampling be undertaken in conjunction with the essential works being managed by Sunwater in 2020. The findings from these investigations will be used to inform preliminary designs and cost estimates for three long-term options:
- maintain the primary spillway height at the level of the essential works (nominally 5.8 metres below existing spillway level prior to the essential works)
- raise the primary spillway height to an optimal level (up to the existing full supply level prior to the essential works)
- lower the primary spillway height to an optimal level (down to a maximum of 10 metres below the existing spillway level prior to the essential works) and explore alternative water supply options.
Dam decommissioning is not recommended.
BUILDING QUEENSLAND ROLE
Building Queensland’s options assessment was informed by an independent design, cost and risk review of Sunwater’s technical information and an independent definition of service needs, assessment of future water demand, and a multicriteria assessment of the five options.
The review of the design, cost and risk of the nominated five long‐term options involved an independent review of technical information supplied by Sunwater, including information on the existing condition of Paradise Dam, available design reports, dam safety and comprehensive risk assessments, and cost estimates for each of the five options.
The second review involved an independent assessment of service needs, the development of projected water demands, the investigation of alternative water supply options, and a multi-criteria analysis of the five options using the identified service needs as evaluation criteria.
Building Queensland undertook targeted stakeholder engagement with key regional industry and community stakeholders to inform the water demand assessment and options analysis. In developing the report, Building Queensland also had regard to several other investigations relevant to Paradise Dam and the surrounding region, such as reports prepared by Tatro Hinds, Adept Economics and Rizzo International Inc.
1Building Queensland was engaged by the Department of Natural Resources, Mines and Energy to undertake the assessment. Sunwater is the project owner.